To improve spectral efficiency in radio transmission (e.g. for a microwave radio link), radio transmission can be performed using orthogonal polarizations. To optimize the use of orthogonal polarizations in radio transmission, it is important that information, or signal energy, does not leak between the two polarizations, i.e. that the polarizations do not mutually interfere. To limit such leakage, the transmit antenna and the receive antennas need to be aligned (rotation-wise) so that a signal transmitted on a first polarization at the transmitter is only, or mostly, received on a corresponding first polarization at the receiver and not on an second polarization at the receiver.
Should some signal energy leak between polarizations, a cancellation of this leakage can be done at a receiver. This cancellation of polarization leakage is sometimes referred to as cross-polarization interference cancellation, XPIC. However, during XPIC, some of the main or wanted signal energy may be lost, and hence polarization leakage may still occur which is not desired.
To align the transmit and receive antennas in polarization, it is typically necessary for an installation person, to manually rotate the misaligned antenna at one end of the communication channel using feedback from another installation person, at the other end of the communication channel. Antennas are usually mounted high up in masts and/or in remote locations. Thus, such a solution is cumbersome and time-consuming. Such a solution also requires designing and providing a mounting arrangement for the antennas that allows mechanical rotation of the antennas, which also increases the cost of the antennas.
Thus, there is a need for a technique addressing at least partly the problems stated above without requiring manual intervention.